The present invention relates to snap fasteners in general, and more particularly to improvements in snap fasteners of the type wherein the male and female components of the fastener can be assembled with one or more discrete retaining and anchoring devices.
Commonly owned German Offenlegungsschrift No. 33 36 550 discloses a snap fastener wherein the female component is preassembled with an anchoring device so that it can be affixed to a carrier (for example, a sheet of textile material) by causing the prongs of the anchoring device to penetrate through the carrier and to be deformed in response to engagement with a suitably configurated cam face in the chamber of a complementary retaining device. An advantage of such construction of the female component of the snap fastener and its attachment to the anchoring and retaining devices is that the attachment of the female component to the carrier is simplified, that mass-production of the snap fastener is facilitated, and that the parts of the snap fastener are less likely to be scratched. The likelihood of scratching a conventional snap fastener is particularly pronounced if the anchoring means comprises sharp prongs which can penetrate into the synthetic plastic material of the male or female component of the snap fastener. The components of the snap fastener are likely to be scratched when a large number of male or female components is dropped into a vessel wherein the synthetic plastic material of such components is contacted by a selected coloring agent. As a rule, such dyeing involves a thorough mixing of female mixing and male components of snap fasteners in a drum. By proceeding in a manner as proposed in the aforementioned German publication, the likelihood of extensive scratching of sensitive plastic components by the prongs of the anchoring devices is greatly reduced. It is particularly desirable to avoid scratching of those portions of a snap fastener which are readily visible when the male and female components are attached to garments or the like. On the other hand, scratching of certain portions of synthetic plastic male and female components is of lesser consequence if such portions are concealed when the male and female components are coupled to each other or are attached to carriers in the form of textile sheets or the like.
The heretofore known snap fasteners exhibit the drawback that the force with which the male and female components are held together is relatively small. It is normally desirable to assemble a snap fastener in such a way that the force which is required to join a male component to a female component is a fraction of the force which must be applied in order to separate such components from each other. Heretofore known proposals involve the selection of dimensions of the male and female components. This can affect the appearance of the snap fastener and is not always likely to ensure that the closing force is substantially smaller than the opening force. Therefore, many conventional snap fasteners are designed in such a way that the magnitude of the closing force approximates the magnitude of the opening force or that the magnitude of the opening force is reduced for the sole purpose of ensuring that it is not necessary to apply a pronounced closing force.